import threading
import time

class SubThread(threading.Thread):
    def run(self):
        for i in range(3):
            time.sleep(1)
            print(f'线程{threading.current_thread().name}正在执行{i}')

if __name__ == '__main__':
    start = time.time()
    print('主线程开始执行')

    lst = [SubThread() for _ in range(2)]

    for t in lst:
        t.start()

    for t in lst:
        t.join()

    print(f'<UNK>{time.time()-start}<UNK>')

